How can someone who has never won a World Chess Championship be rated above most World Chess Champions?

Because best players and greatest players are two different things. I think Carlsen plays stronger moves than Steinitz did, but I think Steinitz career achievements make him a greater player. If "five best players" mean the players that played the "best" chess I'd rank Carlsen ahead of Steinitz, if it's a question of the greatest players based on career achievements I'd rank Steinitz ahead of Carlsen.

How can you be sure that Karpov played better than Carlsen does? Chess has evolved since Karpov was the best player in the world 30 years ago. I don't think Karpov necessarily played better than Anand and Kramnik at their best either. He was a greater player but if he played better chess is hard to evaluate.

"Gelfand is the challenger for the World Chess Championship what does that tell you about the state of chess at the moment?"

Nothing wrong with the state of chess itself, just like when Khalifman and Kasimdzhanov won their knockouts. What's wrong is rather having knockouts decide important matters, but since only Carlsen protested about that cycle change FIDE used that format one more time, and once again a player far from the top won.

"It was published in 2006 and these experts don't even have Carlsen in their list of 101 greatest of all times. IMO if they retooled and reprinted it in 2012, they would include Carlsen but he wouldn't be even top 10 of all time, let alone top 5. IMO at this point in his career he should be ranked after Spassky (#11 on their list)"

No one ranked the 15-year-old Carlsen as one of the greatest players ever, when that list was made he was in the lower 2600s. If Keene and Divinsky wouldn't rank him top ten among the greatest players ever today it wouldn't be hard to understand, I don't rank him there myself. But ranking Spassky as the greater player of the two doesn't equal stating that Spassky played better chess in the 1960s than Carlsen does in the 2010s.

"He (Carlsen) doesn't YET have a plus score against his contemporaries on the backside of their careers!!!"

The question is if Carlsen's scores five years ago define his level today. Carlsen's -1 against Kramnik is caused by a loss when Kramnik was World Champion and Carlsen 16 and far from a top ten player. Also Carlsen's minus against Anand was hardly the result of Anand in the dawn of his career vs Carlsen on the top. Anand was World Champion and consecutive Linares winner when Carlsen lost four games before reaching top ten.

One could just as well pick Aronian's 6-1 against Anand during the latter's World Champion years and draw conclusions from that, but one or two head to head career scores say little about who is playing the best chess today. A bigger comparison could look like this, only including years when Anand was a top player and/or World Champion but many games from long before Carlsen reached top ten level.

Anand vs Aronian 1-6Carlsen vs Aronian 6-4

Anand vs Radjabov 2-2Carlsen vs Radjabov 5-1

Anand vs Nakamura 0-1Carlsen vs Nakamura 5-0

Anand vs Ivanchuk post-2000 1-2Carlsen vs Ivanchuk 8-2

Anand vs Topalov 13-12Carlsen vs Topalov 8-3

Then Anand is +1 against Kramnik while Carlsen is -1, but how conclusive those stats are with regards to Carlsen's playing level today is hard to say. I think it's difficult to say if Carlsen at his best plays better moves than Karpov at his best, maybe, maybe not. Karpov had more time for his moves, and the advantage of adjournments when his very strong seconds could help him with endgame analysis.

"To compare Carlsen to even Karpov is ludacris. Karpov thoroughly dominated the chess world for 10 years!"

Steinitz and Lasker dominated chess for longer periods than that, but how long a player dominated the chess world doesn't have to say much about if he played stronger moves than the best players today.